Question
Prove the following identities: $\sec^2\theta + cosec^2\theta = \sec^2\theta\ cosec^2\theta $.

Answer

LHS = $\sec^2\theta + cosec^2\theta$
$=\frac{1}{\cos ^2 \theta}+\frac{1}{\sin ^2 \theta}$
$=\frac{\sin ^2 \theta+\cos ^2 \theta}{\sin ^2 \theta \cdot \cos ^2 \theta}$
$=\frac{1}{\sin ^2 \theta \cdot \cos ^2 \theta}$
$=\frac{1}{\sin ^2 \theta} \times \frac{1}{\cos ^2 \theta}$
$= \sec^2\theta\ cosec^2\theta$
= RHS
Hence proved.

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